NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS62 KGSP 290828 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 328 AM EST Wed Nov 29 2023

SYNOPSIS
High pressure will linger over the region leading to continued dry weather into Thursday night, and chilly temperatures today.
Moisture will return from the west beginning early Friday, with rain chances off and on through the weekend as low pressure systems move through the Eastern states.

NEAR TERM /THROUGH TONIGHT/
As of 315 AM EST Wednesday: Dry sfc high pressure directly overhead is leading to clear skies and great radiational cooling conditions this morning. Temps this morning will be the coldest we have seen so far this fall, with lows expected to fall into the teens in the NC mountains, and the teens to the lower 20s elsewhere. Did go ahead and bump up lows a few degrees compared to the previous update as temps were running a bit warmer than forecast. Otherwise, lingering low-end wind gusts will lead to single digit wind chills through the mid-morning hours for elevations above 5000 ft and across portions of the the northern NC mountains.

The sfc high will remain overhead throughout the duration of the near term period, leading to lighter winds as well as continued dry weather. Winds will gradually turn to the SW late this morning into early this afternoon, but gusts any low-end gusts that develop should be limited. Highs this afternoon across the NC mountains will be ~5-10 degrees warmer compared to yesterday. Highs elsewhere should be somewhat similar to yesterday's, climbing back into the upper 40s to lower 50s. Despite sunny skies leading to great insolation through this afternoon, highs will still end up around 5- 10 degrees below climo. RH values are expected to drop into the low to mid 20s this afternoon across much of the forecast area. An SPS for Increased Fire Danger was issued for NE GA with RH values dropping below 30% this afternoon and evening. Please see the Fire Weather discussion below for more details. Upper clouds will gradually increase from the west this evening into tonight, limiting radiational cooling somewhat. Despite the cloud cover, lows will still be cold, dropping into the mid 20s and lower 30s tonight.

SHORT TERM /THURSDAY THROUGH FRIDAY/
As of 130 AM Wed: Offshore sfc high, supported by low-amplitude upper ridging, will promote SW'ly flow into the area Thursday. Thicknesses will continue to rebound and temps will follow, returning to about normal. Attention then turns to the compact shortwave moving NE out of the Texas Panhandle region, and developing sfc low. Deep moisture advection will occur across the Southeast at large as this system moves toward the lower Great Lakes and weakens by Friday morning.
Over our CWA, the offshore high will remain in place at the surface as isentropic lift and moistening develops from the top down Thursday night. Model QPF begins no sooner than it did on yesterday's runs.
The forecast remains challenging given that cloud cover could not arrive soon enough to inhibit radiational cooling. Upper level RH increases enough as heights fall aloft that some alto/cirrus are likely to be seen. Furthermore, with the WAA creating a warm nose profile, raw models suggest southerly flow will warm temps overnight across the mountain ridges if not valleys and even some Piedmont areas. Due to the warm nose, freezing rain or drizzle would be the primary concern unless evaporational cooling proved enough to bring some snow/sleet down to the surface. All this said, the most likely scenario is that sfc temps will be above freezing in almost all locations, although some snow/sleet could still mix in with rain in those colder mountain areas. Even if this setup doesn't lead to academic in-situ CAD, it certainly could be described as a lookalike event in terms of the sensible wx.

Dynamic support will diminish as the low tracks north of the Ohio River Friday, even as the warm conveyor belt and deepest moisture rides over the CWA, so the best PoPs and QPF continue to be forecast in the middle of the day. Subtle differences in models' low tracks lead to a noticeable spread in the forecast later Friday into early Saturday, so fcst confidence decreases Friday afternoon and PoPs trend lower. Precip may not completely taper off, although cloud cover is likely to remain abundant thru the end of the day.
Reflecting the in-situ CAD or lookalike, Friday will be cooler than Thursday and rather chilly in most areas, with the heart of the Piedmont likely remaining in the 40s thru the day.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
As of 200 AM Wed: A deep longwave trough will be present over the western CONUS and northern Mexico late Friday. The upper level gradient will sharpen as the trough begins to move east, and as jet amplifies from Texas to the Northeast states, upper divergence will develop over a quasi-stationary boundary near the Gulf Coast--the orphaned cold front from the low described in the short term. A weak sfc wave should develop in response, and is expected to track northeast across our CWA. Model spread in the location/timing of this development maintains lower than average confidence in the forecast Friday night and Saturday, but chance to low likely PoPs will be maintained in that period, ticking upward late Saturday when models are in somewhat better agreement.

Warm moist southwest flow does not look to really shut off until the sfc wave exits our area to the east and low-level CAA occurs. Models variously depict that happening Sunday or early Monday, as sfc low moves thru the eastern Great Lakes. If CAD indeed becomes established early Friday, it likely won't be scoured out until the CAA begins; thus max temps could remain on the cold end of the envelope Saturday if not Sunday. Went ahead and blended in some colder guidance to limit maxes Saturday. A modest 25-30kt 850mb LLJ will precede the cold front, and if there is a retreating wedge front Sat night or Sunday, low-level shear would be enhanced. Some of the global solutions show a small amount of SBCAPE developing in the area, so a marginal high-shear low-CAPE severe event is not out of the question.

Whatever precip occurs from the weekend event should be rain.
Northwest-flow precip is possible as the main trough axis passes, but again models vary as to when that happens. Monday night timing depicted on GFS and 00z EC is similar to what those models showed 24 hours ago. An embedded shortwave coming later will give another chance Tuesday night, and light snow appears more likely then. Temps will trend colder toward the middle of next week.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/
At KCLT and elsewhere: VFR and dry through the 06z TAF period thanks to surface high pressure over the Southeast. Winds will be mostly light and variable to calm across most of the terminals through daybreak. Wind direction will be NW at KAVL, with NE winds elsewhere. Winds will gradually turn towards the SW late this morning into early this afternoon, while gradually increasing in speed. Winds will be much lighter compared to yesterday, only reaching 5-8 kts by this afternoon. Any low-end gusts that manage to develop should be limited. Skies will remain clear through this afternoon. A few high clouds will stream into the region from the west this evening into tonight.

Outlook: Dry high pressure will linger into Thursday night, allowing VFR conditions to continue. Moisture and associated restrictions will return from the west starting early Friday, lasting through the weekend.

FIRE WEATHER
Dry conditions are expected again across the western Carolinas and northeast Georgia today. Critical relative humidity values below 30% are expected, along with continued dry fuels and brush. As a result, a Fire Danger Statement was issued for northeast GA for this afternoon and evening. Criteria will not be met for our NC & SC counties as winds will lighter than yesterday.

GSP WATCHES/WARNINGS/ADVISORIES
GA...Increased Fire Danger from noon EST today through this evening for GAZ010-017-018-026-028-029.
NC...None.
SC...None.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Greer, SC,